The prior art, as exemplified in U.S. Pat. Nos. 1,853,634, 1,890,336, 2,327,562, 2,591,948, 2,862,274, 3,067,476, 3,089,328, 3,226,788, 3,449,803, 3,798,714, 3,823,446, 3,968,545 and 4,048,698, contains a number of sliders for slide fasteners and/or slide fasteners employing such sliders. Generally, a slider for a slide fastener, as indicated generally at 42 in FIG. 7, includes two wing members (only one wing member 44 shown in FIG. 7) which are held in a parallel, spaced overlying relationship by a connecting divider post 46 extending between and connecting one ends of the wing members. Flanges 48 and 50 on lateral edges of one or both of the wing members extend toward the other wing member or members and in combination with the divider post and inner surfaces of the wing members define a Y-shaped channel through which fastening elements 34 and 36 on inner edges of carrier tapes 30 and 32 pass in opening and closing of the slide fastener. Parallel portions 52 and 54 of the flanges 48 and 50 define a main channel portion 56 of the Y-shaped channel for receiving the slide fastener elements on the opposite tapes in an interlocking condition. The remaining portions 58 and 60 of the flanges diverge outwardly on opposite sides of the divider post to form, in combination with the divider post, two divided or branch channel portions 62 and 64 of the Y-shaped channel.
The above U.S. Pat. Nos. 1,890,336, 3,226,788, 3,449,803, 3,798,714 and 3,823,446 disclose locking projections on the outer ends of the diverging flange portions of the slider. These prior art flange locking projections must be positioned on the outer ends of diverging flange portions away from the inner regions of the branch channel portions to avoid lockingly engaging the fastening elements during normal opening and closing movement and to avoid forcing the fastening elements against the inner surfaces of the divider post and making slider movement more difficult. The above U.S. Pat. No. 1,853,634 and No. 2,591,948 disclose notches formed on the inside surfaces of the diverging flange portions. The notches are recessed from the normal surfaces of the flanges engaged by the fastening elements during movement of the slider, and where the notches are adjacent the inner regions of the branch channels, any substantial projections into such regions must be avoided or else undesired locking of the slider or greatly difficult slider movement results. These prior art projections and notches only lockingly engage the heel portions of the coupling elements when the slide fastener tapes are pulled apart above the slider. In some articles, for example car seat covers, the upper ends of the tapes are sewn together preventing the upper ends from spreading and thus rendering the locking features of such sliders ineffective. Additionally these prior art sliders generally require additional steps in forming the projections or notches such as bending, deforming, etc., or require complex die casting mechanisms.
The above U.S. Pat. No. 4,048,698 discloses a locking pawl with a portion arranged centrally in one wing and formed by making cuts in the wing and by bending a part of this wing into an inverted V-shaped configuration. This pawl, besides requiring the extra cutting and bending steps, also requires very close tolerances with the fastening elements on the tapes of the slide fastener in order to engage the fastening elements while permitting movement of the slider on the slide fastener. To produce such close tolerances, the dimensions of the slider as well as the dimensions of the fastening elements must be carefully controlled in manufacture since variations in these sizes can cause the locking pawl to be ineffective or greatly increase the force required to move the slider on the slide fastener elements. Furthermore, to be effective, this locking pawl must engage the slide fastener elements at all times resulting in increased forces required to move the slider.
The working edges or working surfaces formed on innermost portions of the connecting divider posts facing the main channel portions in the prior art generally either extend straight and perpendicular between the inner faces of the wing members or, as illustrated in the above U.S. Pat. No. 3,067,476 and No. 3,798,714, extend from superposed positions at the inner surfaces of the wing members at opposite and equal outwardly extending oblique angles to form centrally disposed notches in the divider post which have their deepest penetration along a plane parallel and centered between the wing members.
In larger size prior art slide fasteners employing coil or spiral coupling elements, the sliders tend to hang up or stop during opening movement of the slider. These coil-type or spiral-type slide fasteners employ fastening elements, such as 34 and 36 in FIG. 7, which are formed from convolutions of respective coils of monofilament thermoplastic configured in a conventional manner. In forming the tapes 30 and 32, weft or filling threads are passed around connecting portions of the monofilament coils between the fastening elements 34 and 36 and are also interwoven with a plurality of warp threads surrounding a cord to form beads 38 and 40 on inner edges of the tapes supporting the fastening elements 34 and 36. Because of the tendency for slider hang up, larger sizes of spiral-type slide fasteners have generally not been commercially successful.
The above U.S. Pat. No. 2,327,562 discloses a divider having a working end which is bluntly rounded to provide a spreading angle for the slide fastener stringers which is obtuse rather than acute as produced by more pointed working ends; this greater spreading angle permits employment of the slider on a slide fastener with the locking projections of the fastening elements pointing in a direction away from the divider, which is the reverse of the conventional direction of the locking projections. The above U.S. Pat. No. 2,591,948 shows a heart-shaped spring assembled around the divider post for forcing the heel portions of coupling elements into notches in the outwardly extending portions of the flanges.
The above U.S. Pat. No. 2,862,274 discloses a slider with a ridge or platform extending on one wing member from the working edge or surface of the divider post for maintaining the fastening elements or scoops in proper position for coupling engagement during the closing movement of the slider. This ridge is illustrated as causing a tilting movement of the fastening element within the slider channel which is formed with a larger dimension relative to the size of the fastening elements in order to avoid jamming of the slide fastener caused by foreign elements or garment flaps in the slider channels.
The above U.S. Pat. No. 3,089,328 discloses a bolt movable by a cam for extending from the divider post into a center portion of the main channel in the slider to block movement of the fastening elements therethrough and thus lock the slider on the side fastener.